1. Field of the Invention
The present invention relates to a method for transmitting/receiving a frame in a mobile communication system.
2. Description of the Related Art
At present, mobile communication systems are being evolved so as to provide various services, such as broadcasting, multimedia images, multimedia messages, etc. In particular, a 4th generation mobile communication system is being developed in order to provide high-speed mobile users with data services at a data transfer rate of 100 Mbps or greater and to provide low-speed mobile users with data services at a data transfer rate of 1 Gbps or greater while departing from services centered on voice and packet data communications.
Most mobile communication systems take account of multiple access schemes so as to efficiently use finite frequency resources. The mobile communication systems also take account of duplexing schemes for identifying two-directional connections. That is, the mobile systems distinguish between an uplink connection and a downlink connection. One such scheme that considers both multiple access and duplexing is a Time Division Duplexing-Orthogonal Frequency Division Multiple Access (TDD-OFDMA) scheme.
FIGS. 1A and 1B illustrate a conventional TDD-OFDMA frame structure and a TDD-OFDMA frame structure with multiple zones, respectively.
Referring first to FIG. 1A, the TDD-OFDMA frame is divided into a downlink subframe and an uplink subframe, and a Transmission/reception Time Gap (TTG) is located between the two subframes. A preamble is located in a first symbol interval of the downlink subframe, and control information is located in a subsequent symbol interval of the downlink subframe. The control information includes a Frame Control Header (FCH), DownLink Media Access Protocol (DL-MAP), and UpLink Media Access Protocol (UL-MAP).
Referring next to FIG. 1B, each of the downlink and uplink subframes may include multiple zones according to subchannel configuration schemes.
In order to reliably transmit data at high speed in a mobile communication system, short latency is required. Here, the short latency refers to latency less than the predetermined threshold latency. For example, short latency may be required to apply Hybrid Automatic Repeat Request (HARQ) to a Voice over Internet Protocol (VoIP) service that is providing a real time service. However, short latency is not required for all packets. Here, latency can be represented by the following expression:Latency=Initial Transmission Time+Retransmission Probability×Retransmission Delay  (1)
That is, latency is determined by an initial transmission time, a retransmission probability and a retransmission delay. In view of the above expression, it can be noted that a retransmission probability or a retransmission delay must be reduced for a packet requiring short latency.
As mentioned above, there may be a packet requiring short latency. Accordingly, a frame supporting short latency must exist in order to transmit such a packet at high speed. Also, in order to transmit both a packet that does not require short latency and a packet that does require short latency in the same system, a frame corresponding to such transmission must exist.